Delivery end cleaning apparatus for carding machines

ABSTRACT

A SUCTION MANIFOLD ASSEMBLY FOR PNEUMATIC CLEANING OF THE DELIVERY END SECTION OF A CARDING MACHINE, INCLUDING A MAIN PLENUM SECTION FORMING A SUCTION CHAMBER ABOVE THE DOFFER CYLINDER IN OPEN COMMUNICATION WITH THE LATTER AND WITH AN ADJACENT PORTION OF THE MAIN CYLINDER, AND A HOOD-LIKE EXTENSION OF HINGED PLURAL SECTIONS OVERLYING MOST OF THE OTHER CARD COMPONENTS IN THE DELIVERY END SECTION. THE MAIN PLENUM SECTION INCLUDES A FIRST EXHAUST PORT IN A SIDE THEREOF CONNECTED TO A SUCTION RISER AND A RETURN TUBE TRAVERSING THE PLENUM SECTION IN PARALLELISM WITH THE AXIS OF THE FIRST EXHAUST PORT COMMUNICATING AT ONE END WITH ANOTHER SUCTION RISER AND AT ITS OTHER END THROUGH AN ELBOW WITH THE PLENUM SECTION TO FACILITATE ATTAINMENT OF SUCTION SOURCE CONDITIONS AT EACH OF THE PLENUM AND MAINTAIN SUBSTANTIALLY UNIFORM PRESSURE ACROSS THE PLENUM.

D. A. SLOAN Oct. 26, 1911 DELIVERY END CLEANING APPARATUS FOR CARDING MACHINES Filed Aug. 28, 1969 4 Sheets-Sheet 1 DONALD A.SLOAN Oct. 26, 1971 D. A. SLOAN 3,614,813

DELIVERY END CLEANING APPARATUS FOR CARDING MACHINES Filed Aug. 28, 1969 4 Sheets-Sheet 2 Oct. 26, 1971 D SLQAN 3,614,813

DELIVERY END CLEANING APPARATUS FOR CARDING MACHINES Filed Aug. 28, 1969 4 Sheets-Shoot 3 INVI'JN'I'UH.

DONALD A-SLOAN D. A. SLOAN Oct. 26, 1971 DELIVERY END CLEANING APPARATUS FOR CARDING MACHINES Filed Aug. 28, 1969 4 Sheets-Sheet 4 O 4 Q d r O O O 3 m .6 3

N w WA m We w w T I A a M 0 L my a M 1 3 E O 5 2 States US. Cl. 19-107 8 Claims ABSTRACT OF THE DESCLOSURE A suction manifold assembly for pneumatic cleaning of the delivery end section of a carding machine, including a main plenum section forming a suction cham' ber above the doffer cylinder in open communication with the latter and with an adjacent portion of the main cylinder, and a hood-like extension of hinged plural sections overlying most of the other card components in the delivery end section. The main plenum section includes a first exhaust port in a side thereof connected to a suction riser and a return tube traversing the plenum section in parallelism with the axis of the first exhaust port communicating at one end with another suction riser and at its other end through an elbow with the plenum section to facilitate attainment of suction source conditions at each side of the plenum and maintain substantially uniform pressure across the plenum.

BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates in general to pneumatic cleaning of carding machines, and more particularly to suction manifold structure for the delivery end region of a carding machine for pneumatically capturing and removing trash and fly being discharged from or released at that region, particularly in the area of the doffer and the adjacent portion of the flats chain.

Much effort has been devoted to the elimination or reduction of escape of fly and trash, usually in the form of a mixture of short waste fibers and assorted dust and trash particles, from carding machines, especially as the problem of fiber and trash escape increases with increasing speeds of operation of the carding machine. It is important to eliminate or minimize the escape of such fibers and trash into the air in the textile machinery room, as the resultant comtamination would produce unhealthy working conditions for the operators, impair the quality of the sliver because of intermingling of the trash therewith, and cause deposits of the contaminants on the machinery in the room, creating fire hazards and interference with proper operation of the machinery.

Various pneumatic cleaning devices have been proposed to effect suction withdrawal of fly and trash from various portions of carding machines to reduce the escape of the fly into the surrounding atmosphere and withdraw it before it becomes intermingled with the sliver. Most frequently, this has taken the form of several pneumatic suction pipes extending transversely across the carding machine and connected to a suction source, the pipes having slots extending along their full length and located in specific zones which form predominant sources of fly and trash escape. To effectively capture and remove the fly and trash from the many locations in the carding machine where discharge of trash and fly is prevalent, both in the lickerin region and in the delivery end region of the carding machine, requires a large number of such pipes disposed at many different locations, since such narrow suction slots are capable of withdrawing trash and fly from only a very limited distance immediately adjacent the slot. Examples of BfiMfilB Patented Oct. 26, 11971 prior efforts to effect pneumatic removal of trash and fly from limited zones are found in the Griswold U.S. Pat. No. 2,683,901; Hayes US. Pat. No. 2,774,994; Fowler et al., US. Pat. No. 3,212,138; and ONeal et al., US. Pat. No. 3,357,062.

As will be appreciated by those skilled in the art, the delivery end region of the conventional carding machine includes a doifer cylinder which rotates in close proximity to the main cylinder or swift of the carding machine and which rotates beneath a doffer cover or bonnet disposed closely adjacent to the periphery of the doffer. A flats chain overlies the upper arcuate portion of the main cylinder and negotiates a flats drive sprocket defining a delivery end bight centered about the drive shaft of the drive sprocket generally above the transfer zone between the main cylinder and the doffer. Customarily, there are provided adjacent the delivery end bight of the flats chain a flats stripping comb which oscillates through a selected stroke to sweep the accumulated strips of short fiber particles of this clothing of the flats bars from the surface of this clothing, as well as a spiral flats brush which brushes any residue in the form of individual fibers loose from the flats, and a hackle comb which cleans the flats brush. It is well known that both the spiral flats brush and the hackle comb shed large quantities of individual fibers out into the room and because of their size and location it is diflicult or expensive to cover them in such a way that suction air can capture and carry away the material that is being centrifuged off of the spiral brush. However, the trash and fibers dislodged from the flats by the flats stripping comb, and by the brush and hackle comb if present, must be removed to avoid undesirable contamination of the sliver or of the air in the room.

Also, the conventional carding machine has a percentage plate which is carefully positioned with its upper edge in close proximity to the flats and to the cylinder to control air currents where the flats leave the cylinder and adjust the amount of cotton that is carried away from the carding process as flats strips relative to the amount that is carried on by the cylinder to be transferred to the doifer. Below this percentage plate there is usually provided a hinged inspection cover as well as a bolted-on front plate that extends the seal all the way down to the junction between the main cylinder and the dofler. In'some cards, the cotton fibers which are transferred from the main cylinder to the dotfer are removed by a stripper roller and transferred by a redirecting roller through crusher rolls, and in other cards the web is stripped from the doifer by a dotfer comb and advanced through the crusher rolls, after which the sliver is drawn through take-01f rolls and fed to the sliver can. Numerous areas on the delivery end region of the carding machine, particularly the transfer zone between the main cylinder and the doffer and the zone of the rolls which receive cotton from the doifer, and the stripper comb, flats brush, and hackle comb, are sources of substantial discharge of trash and fly.

It is believed that the intersection of the close fitting dotfer cover and the front plate below the percentage plate is detrimental to proper carding operation since windage builds up between the clothing of the respective cylinders and the underside of the plate and this windage must be dissipated in some manner at the contact point between the two cylinders.

An object of the present invention, therefore, is the provision of a novel suction manifold structure for use in the delivery end region of carding machines to define a low pressure low velocity suction chamber which includes substantially all the components on the delivery end region of the card from which waste and fly normally originate to capture and remove this fly and trash.

Another object of the present invention is the provision of a novel suction manifold structure as described in the preceding paragraph, wherein a main suction plenum is defined above the doffer cylinder and substantially uniform suction conditions are established at opposite lateral sides of the main plenum section, the suction conditions established at one side of the main plenum section being produced by a return tube which transversely spans the plenum section so that the suction risers or ducts to the main suction source are connected to only one side of the manifold structure.

Yet another object of the present invention is the provision of a novel suction manifold structure for the delivery end region of a carding machine, which eliminates the need for any close fitting dolfer cover over the doffer cylinder and which permits ready inspection of and access to the components of the carding machine covered by the manifold structure.

Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a fragmentary side elevation view of a carding machine with the suction manifold assembly of the present invention positioned thereon;

FIG. 2 is a vertical section view, to enlarged scale, of the manifold structure and the associated portions of the delivery end section of the carding machine, taken longitudinally of the carding machine;

FIG. 3 is a perspective view of the main plenum section of the suction manifold structure;

FIG. 4 is an elevation view of the foot end of the main plenum section, as viewed from the position of line 44 of FIG. 2; and

FIG. 5 is a horizontal section view of the main plenum section taken along line 5-5 of FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, there is shown in somewhat schematic or diagrammatic form, the delivery end portion of a standard carding machine including a main cylinder or swift 12 and the usual flats chain 13 defining a delivery end bight at one end where it is trained about a flats chain sprocket 14 on shaft 15 positioning the flats chain 13 so that the lower reach thereof immediately overlies the upper portion of the main cylinder over a substantial circumferential extent. Also shown are the usual doffer 16, the stripper roller 17 and redirecting roller 18, and the crusher rolls 19 between which the sliver is delivered through take-ofi rolls 20 in the conventional manner to the sliver can. While the type of carding machine herein shown employs the stripper roller 17 and redirecting roller 18 for withdrawing the cotton web from the doffer 16 and transferring (it to the junction) it to the junction between the crusher rolls, it will be apparent that the present invention will be equally applicable to carding machines wherein the web is withdrawn from the dolfer by a dofler comb. Adjacent the delivery end bight of the flats chain 13 are the usual oscillatory flats stripper comb 21, flats spiral brush 22, and hackle comb 23.

The suction manifold of the present invention is indicated generally by the reference character and may be described broadly as a plurality of hinged interconnected sections including a main plenum section 26 removably fixed to the carding machine to provide support for the whole manifold assembly, a top baifle section 27 extending forwardly and upwardly from the main plenum section 26 in hinged relation adjacent the hackle comb, a dolfer hood extension section 28 hinged to the main plenum section 4 26 and overlying a portion of the doti'er 16 and the stripper roll 17, and a transparent web cover 29 hinged to the doffer hood extension section 28 and overlying the remaining portion of the delivery end of the carding machine.

Referring more particularly to the details of construction of the main plenum section 26, the main plenum section comprises a pair of side plates 30, 30', of similar pro file and construction, each formed of sheet metal having broken flanges along the perimeter thereof at edges 30a, 30b, 30c, 30d and 30e, broken in the proper direction for use of the side plates as right hand and left hand plenum sides, and having a pair of substantially circular openings 31 and 32, the circular openings 32 being interrupted by an edge portion of the side plates as shown. When the flanges of the side plates 30, 31 are broken outwardly, the side plates define downwardly concave arcuate lower edges 30a bounded by outwardly directed flanges to which are spot welded a curved bottom plate 33, formed for example, of a curved aluminum sheet having a broken flange 33b running the width of the sheet which is folded upwardly against the edges 30d and spot welded to the flanges at edges 30d. The bottom plate extends on each side approximately one inch past the plane of the plenum side as indicated at 33a, forming lateral lip portions by which the main plenum section is supported on and fastened to the upwardly convex surfaces of the usual stationary side plates of the carding machine flanking the doifer cylinder, for example, by screws or bolts extending through accommodating openings in the outwardly projecting portions of the bottom plate and into tapped openings in the carding machine side plates.

An angular top plate 34 which also spans the width of the suction manifold assembly has a first top panel 35 lying in a substantially horizontal plane and a second panel 36 inclining downwardly therefrom toward the main cylinder 12 in the region below the delivery end bight of the flats chain, which panels are respectively spot welded at their edges to the flanges at the correspondingly shaped edges 30b and 30c of the side plates. The inclined panel 36 has a broken flange 36a running the width thereof at its lowermost edge spot welded to the broken flange 33b of the bottom plate and forming therewith the upwardly inclined lip formation 36b at the foot of the main plenum section 26. A narrow front cap 37 which spans the width of the plenum section 26 is also spot welded to the outwardly broken flanges at the short edge 30e of the side plates extending between the front or left hand end of the plenum section 26, as viewed in FIGS. 1 and 2, and the second circular openings 32 therein. Short tube sections 38, 38' are welded to the side plates 30, 30' concentric with the openings 31 therein to form nipples or duct fittings at the opposite sides of the plenum section, and a return tube 39 which is of slightly greater axial length than the width of the plenum section and has an outer diameter corresponding to the diameter of the openings 32 is fitted in the openings 32 and welded into position. A degree elbow section 40 of tubing having a diameter approximating that of the return tube 39 and the short tubes 38, 38 is fitted onto and sealed on one end of the return tube 39 and on the short tube at the corresponding side of the plenum section, for example, the short tube 38'. The other end of the return tube 39 and the other short tube 38 are each connected by suction riser ducts 41, 42, leading to the lint collecting facility of the air handling system of the mill, for example, the filter unit coupled to the main suction source, indicated diagrammatically at 43, through which suction is applied to the various manifolds of the carding machines and at which the lint and usable cotton fibers are collected.

Also provided on the front edge of the first top panel 35 is a hinge half which is pinned to another hinge half at the lower edge of the top baflle section 27 to define a hinge 44 having a hinge axis located directly above the axis of the return tube 39 to support the top baffle 27. As

is apparent from the drawings, the top baffle 27 comprises a main panel portion 27a which is merely a planiform sheet hinged at its lower end to the main plenum section 26 by the hinge 44 secured to the top plenum wall member 34 and extends upwardly to a level slightly beyond the hackle comb support rod present on the standard carding machine so that it can rest directly upon the hackle comb support rod. The uppermost portion of the top bafile forms a rectangular planar panel 27b which is inclined to the plane of the main panel portion and extends into partially overlying relation to the flats spiral brush 22.

Also secured, as by spot welding, to the front edge of the front cap 37 is another hinge half, which is pinned to a hinge half on the rear edge of the doifer hood extension section 28 to define a hinge 45 by which the doffer hood extension is hingedly supported from the main plenum section 26 at its edge adjacent the main plenum section. The doffer hood extension section 28 is simply a piece of sheet metal bent into a U-shaped transverse cross-section which forms a cover over the portion of the doffer 16 not covered by the main plenum section 26 and also extends over some carding machine components adjacent the dotler in the direction of the sliver can. The extension section 28 comprises a flat top panel 46 and depending side flanges 47 which extend down from the top panel 46 to keep air from entering too freely from the sides of the card. The lower free edge of the depending side flanges 47 may rest at some point on lateral frame portions of the card, for example, on the top of the housing for the bearings for the stripper roller, or angle feet may be provided on the side flanges for releasably fastening them to a stationary component of the card, to support the doffer hood extension section in appropriate position.

The dotfer hood extension section 28, which is hinged at the transverse edge of the top panel 46 nearest the main plenum section 26 to that section by hinge 45, is also hinged at the opposite transverse edge of the top panel 46 by hinge 48 to the web cover 29 to permit the web cover 29 and the doffer hood extension 28 to be swung upwardly from their normal covering position to permit access to the card components therebeneath. The web cover 29 is preferably a transparent panel, formed, for example, of plexiglass, to permit continuous observation of the web and underlying card components and, for example, is supported at an appropriate position by resting its shorter transverse edge nearest the sliver can on the bearings for the take-out rollers at the delivery end of the carding machine.

It will be noted that the entire assembly is so constructed that the transparent web cover 29 can be folded directly back onto the doffer hood extension section 28 so that the rollers of the card beneath the web cover can be inspected more carefully or touched if necessary. If still further access to the card cylinders is required, the folded assembly of the web cover 29 on the doffer hood extension section 28 can then be folded upwardly about the hinge 45 until the region adjacent the hinge 48 rests against the front baffle 27 where it will stay since its center of gravity has gone past the vertical center line of hinge 45.

The arrangement of the components of the main plenum section 26 are such as to define a doffer intake orifice 49 bewteen the lowermost external surface portion of the return tube 39 and the confronting adjacent portion of the upwardly convex bottom plate 33, which doffer intake orifice spans the full width of the plenum section corresponding to the width of the card. It will be noted that the downwardly convex portions of the return tube 39 between the front cap 37 and the portion of the return tube nearest the bottom plate, and the upwardly convex portion of the bottom plate 33 extending from the open front end 50 of the plenum section 26 to the portion of the bottom plate nearest the return tube 39 collectively define a smooth converging entry throat to the doffer intake orifice 49 which has been found to be much more efficient than the square edge type of doffer intake orifice normally provided in such manifold structures, as less pressure loss results when the air stream enters the smooth entry throat to the dolfer intake orifice 49 and also less pressure loss results when the air stream again expands in the plenum on the back side of the orifice 49.

In addition to the dolfer intake orifice 49, two choke removal orifices 51, 51' are provided in the foot of the main plenum section 26 define-d by the bottom plate flange 3311, these choke removal orifices being of relatively short length and disposed adjacent the opposite lateral edges of the plenum section 26. These choke removal orifices are provided to remove the fluffy balls of waste which will normally float at the juncture of the main cylinder 12 and doffer cylinder 16 and convert to a hard cotton rope or choke if allowed to attach to stationary parts of the card near the side. This fiuffy Waste exists across the width of the junction of the cylinders 12 and 16, but does not harden in the mid-section and either migrates to side orifices or is eventually processed through, so that choke removal orifices need not be provided in the center region of the foot defined by the bottom plate flange 33b.

Additionally, a long strip intake orifice 52. is provided in the top plate panel 36 immediately adjacent the lip formation 36b to span the width of the plenum section 26 and provide an intake orifice for removing the strips which fall from the zone of the delivery end bight of the flats chain 33, and the combs 21 and 23 and flats spiral brush 22. This strips intake orifice 52 may be readily closed with a flat sheet should the user elect to collect the strips in piles, or may be left open when at Thompson roll is used to collect the strips so as to aid in the removal of dust and fly.

As previously mentioned, one end of the return tube 39, and the nipple formed by the short tube 38 at the corresponding end of the plenum section, are connected to suction risers such as risers 41 and 42 to apply suction to the interior of the return tube 39 and to the plenum chamber formed within the plenum section 26. The connection of the suction riser 41, of course, to the nipple formed by the short tube 38 forms a suction source Within the plenum chamber immediately adjacent the side 30 of the plenum section. The suction applied to the interior of the return tube 39 is communicated through the tube, isolated by the return tube walls from the plenum chamher, to the elbow 40 and through the elbow and nipple formed by the short tube 38' to the interior of the plenum chamber immediately adjacent the opposite side plate 30. Thus, suction risers are established on only one side of the differ hood plenum while still maintaining a suction source on each side of the plenum. By this arrangement, wherein all riser connections are on one side of the plenum, the opposite side of the card is maintained more accessible in the strips removal region of the carding machine, thus decongesting the strips removal region. Furthermore, by use of this return tube arrangement, ready access to the interior of the plenum is allowed at the plenum side opposite the suction riser. Ready access to this region is quite important for both the manufacturing process and the card cleaning process; during imaniufacture, frequent careful inspection of the interior is required to detect burrs and formations which would form waste capturing and anchoring points, and during operation in the field, accessibility is important to enable the carding machine attendant to carry out the desired cleaning and maintenance responsibilities. Also, the arrangement of the return tube 39 so that its downwardly curving lower portion approaches the upwardly curving portion of the bottom plate to define intake orifice 49 with the converging entrance throat, provides a most efficient entrance orifice for the air and an eflicient expanding means for the air after entering the orifice. The return tube also allows for the construction of the plenum without internal flanges which run the width of the plenum, it permits the dotfer hood to be either left handed or right handed, and it results in reduction of required parts for fabrication.

The manifold assembly is simply mounted on the carding machine by fastening the extended edges of the bottom plate 33 of the main plenum section 26 to the dotfer cylinder side plates of the carding machine after removal of the dofier cover. The extended edges of the bottom plate are simply drilled to mate with the drilled and tapped mounting holes in the doffer cylinder side plates vacated by the removal of the dofler cover, and the plenum section being then bolted into place using the mounting holes in the doffer cylinder side plates.

What is claimed as invention is:

1. In a carding machine having a main cylinder and a delivery end region including a doffer cylinder having a portion adjacent the main cylinder a a transfer zone for doffing fibers therefrom, web transfer means for transferring the fibers from the dofler cylinder as a web to the delivery end of the carding machine, a flats chain of clothed flats having a delivery end bight spaced above the doifer cylinder, and a flats comb adjacent the bight for sweeping accumulated fiber strips from the flats clothing; a suction manifold assembly overlying said delivery end region for capturing fly and trash in said region and removing the same to an external collecting station including a main plenum section transversely spanning the width between opposite sides of the carding machine and overlying the dofler cylinder having first and "second ends respectively nearer the main cylinder and the delivery end, said plenum section including vertical side Walls adjacent the opposite sides of the carding machine, a transverse end wall at said first end, and top and bottom walls collectively defining an interior plenum chamber having a main intake orifice at said second end opening toward said delivery end, said bottom wall being spaced above the periphery of said doffer cylinder and in open and direct pneumatic communication throughout with an upper sector of the doffer cylinder extending from the transfer zone between the main cylinder and the dofler cylinder over a major portion of the upper half of the dofier cylinder, said side Walls each having a first side opening adjacent said intake orifice aligned along a common transverse axis for receiving a tube therethrough and a second side opening spaced toward said first end from the axis of said first side openings, a return tube spanning the length of said plenum section and extending tthrough said first side openings of both said side walls in sealed relation to the edges of said openings, elbow conduit means extending from one end of said return tube externally of a first one of said side walls to the second side opening in said first side wall, and suction riser means to one side of the plenum section coupling a suction source with the other end of said return tube and with the second side opening in the other side wall whereby suction pressure is applied to the interior plenum chamber defined by said plenum section inwardly adjacent each of said opposite side walls, said return tube extending below the level of said top wall and having a downwardly convex cylindrical surface portion spanning said plenum section defining a convergent throat inwardly adjacent said intake orifice followed by a divergent transition portion leading into said interior plenum chamber.

2. Apparatus as defined in claim 1, wherein said top wall includes a downwardly inclined portion converging toward said bottom wall and toward said first end and extending generally toward said transfer zone to define a foot portion at said first end generally underlying the delivery end bight of said flats chain, and means co-acting with said inclined portion of said top wall to define an 8 upwardly opening trough formation for collecting strips and trash released from said delivery end bight, said inclined top wall portion having an elongated strips intake orifice substantially spanning the width of the plenum section immediately adjacent said trough formation for suction intake of strips into said plenum chamber.

3. Apparatus as defined in claim 2, wherein said transverse end wall at said first end has a pair of choke removal orifices facing said transfer zone and located imme diately adjacent said opposite side Walls for suction removal of fluffy balls of waste which normally float in the region of said transfer zone.

4. Apparatus as defined in claim 3, wherein said manifold assembly includes a hood section hingedly connected to said main plenum section and extending therefrom substantially to the delivery end of the carding machine in covering relation to the Web extending from said doifer cylinder to said delivery end defining a second plenum zone overlying the web and communicating with the first plenum zone to establish air currents for capturing fly and trash released in the second plenum zone and conveying the same into said first plenum zone.

5. Apparatus as defined in claim 1, wherein said transverse end wall at said first end has a pair of choke removal orifices facing said transfer zone and located immediately adjacent said opposite side walls for suction removal of fluffy balls of waste which normally float in the region of said transfer zone.

6. Apparatus as defined in claim 1, wherein said manifold assembly includes a hood section hingedly connected to said main plenum section and extending therefrom substantially to the delivery end of the carding machine in covering relation to the web extending from said dofferZ cylinder to said delivery end defining a second plenum 'zone overlying the web and communicating with the first plenum zone to establish air currents for capturing fly and trash released in the second plenum zone and conveying the same into said first plenum zone.

7. Apparatus as defined in claim 6, wherein said hood section includes a first hood member having a top Wall and depending side walls hinged to said first section for movement from a lower position covering parts of said web transfer means immediately adjacent said withdrawal zone to an upwardly open position exposing said parts and a second hood member of transparent sheet material extending from said first hood member to a position adja- {cent said delivery end and hinged to said first hood member for movement to an upwardly open position exposing portions of the web.

8. Apparatus as defined in claim -1, wherein the carding machine includes a flats brush adjacent said bight and the manifold assembly includes a top balfle member hinged at its lower end to said top wall adjacent said return tube and having a first panel extending upwardly from said hinge to at least the level of said flats brush and a second panel extending at an angle to said first panel in partially overlying relation to said brush to induce air currents downwardly between said top bafile member and said bight.

References Cited UNITED STATES PATENTS 2,683,901 7/1954 Griswold 19107X 3,376,610 4/1968 Williams 19107 3,387,337 6/1968 Crowley, Ir. 19107 FOREIGN PATENTS 762,403 11/1956 Great Britain 19-107 OTHER REFERENCES Japanese Patent Publication (Fuji) No. 38-1025 pub lished Feb. 14, 1963.

DORSEY NEWTON, Primary Examiner 

